1. Field of the Invention
The present invention relates to a piston assembly, and more particularly, to a locking piston assembly.
2. Statement of the Problem
A piston assembly comprises a piston head positioned in a piston chamber. The piston head moves reciprocally in the piston chamber in response to the introduction and/or removal of a pressurized liquid or a pressurized gas. One type of piston assembly is a piston actuator that can be used to convert fluid pressure into mechanical work or vice versa. The piston head is coupled to a piston rod. The piston rod can be connected to any manner of mechanism or device, wherein the piston assembly can be operated in a reciprocating manner and therefore can be used to perform mechanical work.
In some applications, it is desirable that the actuator be locked in an extended position, be locked in a retracted position, or both. For example, in industrial or manufacturing equipment, a locking piston assembly may be needed for purposes of safety of human operators. This includes a locking capability in the event of the loss of a pressurizing fluid used in the piston assembly.
In the prior art, a mechanical lock typically includes a pin or tab that must hold the piston head and piston rod against a force created by a pressurized hydraulic fluid. This forces the lock mechanism to be unnecessarily robust, large, and heavy.